Browse Topic: Braking systems
This SAE Standard covers motor vehicle brake fluids of the nonpetroleum type, based upon glycols, glycol ethers, and appropriate inhibitors, for use in the braking system of any motor vehicle, such as a passenger car, truck, bus, or trailer. These fluids are not intended for use under arctic conditions. These fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR) or a terpolymer of ethylene, propylene, and a diene (EPDM).
This study investigates an optimal control strategy for a battery electric vehicle (BEV) equipped with a high-speed motor and a continuously variable transmission (CVT). The proposed dual-motor powertrain model activates only one motor at a time, with Motor A routed through a CVT and Motor B through a fixed gear. To improve energy efficiency, two optimization methods are evaluated: a quasi-steady-state map-based approach and a dynamic programming (DP) method. The DP approach applies Bellman’s principle to derive the globally optimal CVT ratio and motor torque trajectory over the WLTC cycle. Simulation results demonstrate that the DP method significantly improves overall efficiency compared to traditional control logic. Furthermore, the study proposes using DP-derived maps to refine practical control strategies, offering a systematic alternative to conventional experimental calibration.
This RP specifies a dynamometer test procedure to characterize wear rates of automotive service brake linings (brake shoes) and disc brake pads.
Increasing the mission capability of ground combat and tactical vehicles can lead to new concepts of operation that enhance safety and effectiveness of warfighters. High-temperature power electronics enabled by wide-bandgap semiconductors such as silicon carbide can provide the required power density to package new capabilities into space-constrained vehicles and provide features including silent mobility, boost acceleration, regenerative braking, adaptive cooling, and power for future protection systems and command and control (C2) on the move. An architecture using high voltage [1] would best satisfy the ever-increasing power demands to enable defense against unmanned aerial systems (UAS) and offensive directed energy (DE) systems for advanced survivability and lethality capabilities.
The ever-increasing prevalence of electric vehicles in the global market continues to push automakers towards more stringent brake drag requirements. As OEMs seek to differentiate themselves with greater vehicle range to offset consumer anxiety as a barrier for entry to EVs, brake caliper suppliers see requirements for zero or near-zero drag at the component level becoming commonplace. Despite this pressure, many practical concerns exist with torque measurement capabilities in the sub 1.0 N-m range. Additionally, the authors have observed an industry tendency to employ suboptimal engineering methodology for assessing drag concerns, with trial and error attempts continuing to perplex engineers more than it provides solutions. This paper will seek to reintroduce to the reader the basic physics of brake drag from a fundamental free body diagram level, review statistical approaches for characterizing the individual forces acting within the caliper, and propose a simple – yet effective
In an earlier publication, it was reported that the pad compressibility measured under 160 bars on NAO formulas keeps decreasing with increasing number of repeated measurements due to unrecoverable residual deformation of the friction material combined with increasing moisture adsorption, which increases the hardness of the friction material. This current investigation was undertaken to find out if this same phenomenon occurs for NAOs under a low pressure of 100 bars during compressibility measurements and under 700N during dynamic modulus measurements. In all cases, it is found that the same phenomenon occurs, meaning that friction materials become permanently compressed without full recovery, making them harder to compress and raising up the modulus. The dynamic modulus of friction material attached to a backplate is found to be lower as compared with the friction material without the backplate, which is caused by more rapid moisture adsorption of friction material pads without a
As Lowmet pad porosity increases, pad hardness decreases; pad ISO compressibility increases; the nominal friction coefficient increases (SAE J2522); and the disc wear/pad wear decreases. Brake squeal occurrence is affected by the total wear of disc and pads; the wear differential between the inboard pad and outboard pad; pad tangential taper; and pad hardness/material damping. Also, pad chamfer shape has a strong influence on brake squeal occurrence.
As the ICE vehicle changes into the EV, we can use regenerative brake. It can improve not only the energy consumption but also reduce the hydraulic brake usage. The less hydraulic brake usage mitigates the heat loading on the brake disc. From this reason, the lightweight brake can be used in the EV. However, when the lightweight brake is applied, the brake NVH can be increased. The optimization design of the lightweight brake should be done to prevent the brake NVH. In this paper, the optimal brake disc thickness and brake interfaces are determined by using of disc heat capacity analysis. The lightweight brake should be optimized by using of the brake squeal analysis. We can verify the results from both analysis and test. Finally, we can have the lightweight brake, which is competitive in terms of cost, weight and robust to the brake NVH.
The growing demand for improved air quality and reduced impact on human health along with progress in vehicle electrification has led to an increased focus on accurate Emission Factors (EFs) for non-exhaust emission sources, like tyres. Tyre wear arises through mechanical and thermal processes owing to the interaction with the road surface, generating Tyre Road Wear Particles (TRWP) composed of rubber polymers, fillers, and road particles. This research aims to establish precise TRWP airborne EFs for real-world conditions, emphasizing in an efficient collection system to generate accurate PM10 and PM2.5 EFs from passenger car tyres. Particle generation replicates typical driving on asphalt road for a wide selection of tyres (different manufacturers, price ranges, fuel economy rating). Factors such as tyre load, speed and vehicle acceleration are also considered to cover various driving characteristics. The collection phase focuses on separating tyre wear particles from potential
This SAE Recommended Practice defines a clearance line for establishing dimensional compatibility between drum brakes and wheels with 19.5-inch, 22.5-inch, and 24.5-inch diameter rims. Wheels designed for use with drum brakes may not be suitable for disc brake applications. The lines provided establish the maximum envelope for brakes, including all clearances, and minimum envelope for complete wheels to allow for interchangeability. This document addresses the dimensional characteristics only and makes no reference to the performance, operational dynamic deflections, or heat dissipation of the system. Valve clearances have not been included in the fitment lines. Bent valves may be required to clear brake drums. Disc brake applications may require additional running clearances beyond those provided by the minimum contour lines. Mounting systems as noted are referenced in SAE J694.
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